In the manufacture of glassware by the conventional blow and blow process using an individual section (I.S.) machine a gob of molten glass is first formed into a parison in a blank or parison-forming mould at a blank station of the machine. The parison is formed in an inverted position at the blank station and is then swung by a transfer and invert mechanism to an upright position at a blow station. The transfer and invert mechanism has neck ring mould parts which define the base of the blank mould cavity at the blank station and which support the parisons while the latter are being transferred from the blank station. The gobs of molten glass are guided through the open top of the blank mould and are drawn into the neck ring mould parts of the transfer and invert mechanism by suction applied to the base of the blank mould, either on its own or, more usually, in combination with pressure air ("settle blow") applied to the top of the blank mould. After an appropriate interval, the suction ("vacuum settle") is removed, the blank mould is vented and then air under pressure ("counterblow air" ) is applied to the base of the blank mould cavity to force the molten glass against the wall of the blank mould to form the parison. The counterblow air is then removed, the blank mould again vented and the blank mould parts opened to allow the parison to be swung away from the blank station by the transfer and invert mechanism.
Hitherto, the application of suction to the blank mould has been controlled by a first solenoid-operated valve, the application of counterblow air by a second solenoid-operated valve and the venting of the blank mould by a third solenoid-operated valve. Thus, three separate valves are assembled to control the application of suction and counterblow air to a blank mould.